Apparatus for assembling spark plugs



Feb. 10, 1942. A. M. B'ROWN Filed July 16, 1938 2 Sheets-Sheet l \M M ,0 4 w INVENTOR ARCH/BALD M. BROWN A'rionulvs Feb. 10, 1942. A. M. BROWN 2,272,882

APPARATUS FOR ASSEMBLING SPARK PLUGS Filed July 16, 1938 2 Sheets-Sheet 2 INVENTOR ATTORNEYS ARCHIBALDM. BROWN Patented Feb. 10, 1942 UNITED STATES PATENT orrlcs APPARATUS FOR ASSEMBLING SPARK PLUGS Archibald M. Brown, Akron, H0, ulignor to The Firestone Tire a; Rubber company, Akron, Ohio, a corporation of Ohio Application Jilly 16, 1988, Serial No. 219,515

6 Claims.

This invention relates to apparatus for assembiing spark plugs, and more especially it relates to improved mechanism for assembling the porcelains and metal washers in metal spark plug shells or the crimped type.

The present invention is an improvement upon the spark plug assembling apparatus shown and described in my previous Patent No. 2,106,451 issued January 25, 1938'. While the apparatus disclosed in that patent functions satisfactorily and assembles spark plugs in a manner superior to that of other apparatus, it still occasionally breaks the porcelains in such operations. This breakage usually is due to variations in the shape of porcelains with the previous type of apparatus being adapted tohandle most but not all of such eccentric, or untrue porcelains.

The general object of this invention is to overcome the foregoing disadvantage of known types of apparatus for assembling spark plugs and to provide apparatus for assembling and centering porcelains in spark plugs without breakage of the porcelains even though such porcelains be of untrue shape;

The foregoing and other objects are achieved by providing a. resilient centering guide for the lower portion of the porcelain while also using a resilient centering member for the upper portion of the porcelain. Thus the centering members can adjust themselves to compensate for slight deviations in the shape of the porcelain irom the true shape.

In the accompanying drawings:

Figure 1 is a vertical section of a spark plug prior to being acted upon by the apparatus of the invention;

Figure 2 is a vertical section of apparatus embodying the invention;

Figure 3 is a vertical section through a second form of apparatus embodying the invention; and

Figure 4 is a' transverse section taken on line 4-4 of Figure 3. 7

Referring to the drawings, Figure 1 shows a spark plug of the crimp type in its initially assembled condition. This spark plug comprises a metal shell ll, having an electrode l2 extending from the bottom thereof and an annular shoulder lid in the bore thereof, in which is received a porcelain ll having an annular flange Ila adapted to mate with the shoulder Ila intermediate its ends. A deformable gasket i4 that is carried by shoulder lid of the metal shell ii supports porcelain l3 thereon while a second deformable gasket i is carried by the upper surmanently assembled by two steps. the first or which comprises simultaneously telescoping the porcelain it down into its seat in the metal shell II and deforming the gaskets i4 and I5, and. secondly the upper edge or the metal shell II is crimped around and down upon the gasket It and the porcelain it to hold them in place. In Figure 2 the apparatus for performing the first or these actions is indicated generally by A while the apparatus for performing the second of these steps is indicated by B.

I The apparatus A includes a die shoe it which carries a die holder ii on its upper surface. The die holder receives a die positioning sleeve l8 therein, which sleeve is of reduced diameter adjacent its upper end to forms. shoulder it thereon. The die positioning sleeve i8 is held in place by an apertured face plate 2| which engages with the shoulder is and is supported by a resiliently supported pressure block 22. A centering sleeve guide 23 is received in the die positioning sleeve is and is secured therein by two resilient bushings 24, which are made of any suitable material such as rubber, the bushings 24 being carried by the guide 23 and slidably received in the die positioning sleeve. Figure 2 shows that the ends of the centering sleeve guide 23 protrude a slight distance from the bushings 24. A centering sleeve 25 is slidably received in the bore of the centering sleeve guide 2| and it extends from both ends thereof. A head 26 is formed on the lower portion of th centering sleeve 25 while a light spring 21 is placed between the head 26 and the pressure block 22 to urge the centering sleeve upward to engage with the porcelain II. Theupper portion oi the centering'sleeve comprises bifurcated arms 2! which have a downwardiy extending, frusto-conical recess 29 formed in their ends, which recess is provided to receive and center the lower end of the porcelain ll. A tubular centering die tn which is adapted to engage with a shoulder on the metal shell If, is slidably received in the die positioning sleeve II and is supported by the bushings 24.

The upper end of the die positioning sleeve i8 is cormtructed to limit the position that the shell ll assumes on the die 20. A tubular support II is received in the die positioning sleeve between the iower portion of the rubber bushings 24 and the pressure block 22 to transmit force applied to the rubber bushings by the die 30 to the pressure block.

Figure 2 shows that the cone shaped recess 29 of the centering sleeve 25 engages with the face of the flange l3a. This spark plug is perlower end of a porcelain in the metal shell suppatent may be used. These means include apunch holder 35 to which is imparted determinate vertically reciprocating movement by any suitable means (not shown). A bushing 36 having threads cut in the lower portion of its bore is secured in the punch holder It by a set screw. This bushing receives and engages with a punch positioning sleeve 11 that is locked in its given position by a lock nut I. The punch positioning sleeve lflhas a small radially inwardly extending flange it formed on its lower end and this conlines a centering punch ll therein which has an annular flange 42 extending downwardly therefrom and outlining a central aperture therein. The flange 42 is adapted to be placed around the porcelain II and engage with the gasket II to press it against the shoulder llo when the punch holder is moved into the position shown in Figure 2. .An annular ring II, which normally is made from rubber, is placed above the center punch II to engage the upper portion of a porcelain while it is being teiescoped into its seat in the metal shell. The ring 44, is backed by lat-tubular spacer it which abuts against nuts 40 that are secured to the punch holder ll. Figure 2 shows the apparatus when some pressure is being applied to the assembled spark plug whereby the ring N is deformed. as shown. and the centering punch ll is raised up from its seat on the flange 30 on the punch holder.

It will be observed that the rubber bushings 24 which mount the centering sleeve guide 23 and thereby thecentering sleeve II in the die positioning sleeve is can be compressed to permit slight. lateral movement of the lower end of the porcelain I! as it is being .tclescoped into the metal shell. 'Thus if the porcelain is of slightly irregular shape the bushings 2 permit the centerlng sleeve 25 to take and retain a slightly eccentric position relative to the metal shell. Such slight eccentricity does not impair the functioning of the assembled spark plug and prevents breakage of the porcelains while assembling the spark plug. This feature of the apparatus differs it appreciably from the rigid lower centering device employed in previous types of centering apparatus. The conical recess 29, being appreciably largerthan the lower end of the porcelain I! does not restrain the porcelain: initial tendency to oscillate as the porcelain is telescoped into position. In all events, the centering. sleeve tends to center the porcelain inthe shell and maintain it there even though not fixedly holding it in such position.

In the apparatus indicated at B, a pressure support carries agtubular member I! that has a reduced diameter r end forming a shoulder I3. The member 52 retained in position by the shoulder Bl engaging with the face plate ii. A shoulder M is formed in the bore of the memher I! and it supports a tubular seat 88 that is received in the member 52. The seat ii! is adapted to receive a spark plug therein and mount it for the operation of crimping the spark plug shell into its final position.

To crimp the metal shell i l, the punch holder 35 carries a punch 56 which has a punch filler 51 secured in its lower end. The punch filler 51 has annular grooves 58 formed in the ends thereof adjacent its bore which grooves are designed to crimp the upper edge of the metal shell ll down upon the gasket IE to retain the spark plug in the position given it by the apparatus A.

Figure 3 shows apparatus constructed in accordance with the invention for centering spark plugs carrying two electrodes Bil and ti on the metal shell. This embodiment of the invention is identical with that shown in A of Figure 2 except that the centering sleeve it has a small. tubular upper portion 63 in place of the bifurcated arms 2!. The end of the portion 83 is beveled inwardly and receives the lower end of the center electrode N of the porcelain to be centered to maintain it in the center of the metal shell in a manner similar to that of the apparatus shown in Figure 2.

Figure 4 indicates that a small clearance remains between the portion I! of the centering sleeve n and the electrodes on the spark plug whereby slight movement of the porcelain may occur in telescoping it into the metal shell and whereby the porcelain may assume a slightly eccentric position in the metal shell.

In accordance with the patent statutes. 1 have illustrated and described the structure and mode of operation of a complete embodiment of the invention. However, it will he understood that various modifications can be made without departing from the scope of the invention as de fined in the appended claims.

I claim:

1. Apparatus for assembling spark plugs including a metal shell and a porcelain received in the shell, said apparatus comprising a relatively stationary positionins sleeve, in. centering sleeve guide received in said positioning sleeve. a rubber bushing carried by said centering sleeve guide and being snugbr received in the bore of said positioning sleeve. said centering sleeve guide protruding slightly from said rubber bushing, a tubular centering die for a tubular metal shell slidably received in said positioning sleeve and being supported by said rubber bushing, supporting means engaging with the lower portion of said rubber bushing, means for forcing a porcelain into telescoped relation with a metal shell on said tubular die, a centering sleeve slidably received in said centering sleeve guide and extending from the ends thereof. and means engaging with the lower end of said centering sleeve to urge it upwardly. the upper end of said centering sleeve being bifurcated and having a downwardly extending. conical recess 0! appreciable size formed therein which is adapted to engage with and center the lower end of the porcelain in the metal shell on said die, said centering sleeve being resiliently positioned for limited lateral movement by said centering sleeve guide and said rubber bushing, whereby the porcelain may move laterally slightly when being telescoped into the metal shell without being broken and still be substantially centered in the shell.

2. Apparatus for assembling spark plugs including a metal shell and a porcelain received in the shell, said apparatus comprising a positioning sleeve, 1;. centering sleeve guide received in said positioning sleeve, a rubber bushing carried by said centering sleeve guide and being snugly received in the bore of said positioning sleeve, said centering sleeve guide protruding slightly from said rubber bushing, a tubular centering die slidably received in said positioning sleeve and being supported by said rubber bushing, supporting means engaging with the lower portion of said rubber bushing, means {3; f ing a porcelain into telescoped r l t a metal shell on said tubular d and a centering s eeve sli y received in said centering sleeve e, the upper end of said centering sleeve having a downwardly extending conical recess formed therein which is adapted to engage with and center the lower end of the porcelain in the metal shell on said die, said centering sleeve bein'g resiliently positioned for limited lateral movement by said centering sleeve guide and said rubber bushing whereby the porcelain may move laterally slightly when being telescoped into the metal shell without being broken.

3. Apparatus for assembling spark plugs including a metal shell and a porcelain received in the shell. said apparatus comprising a positioning sleeve, 9, centering sleeve guide received in said positioning sleeve, a rubber bushing carricd by said centering sleeve guide and being snugly received in the bore 01 said positioning sleeve, a centering die slidably received in said positioning sleeve and being supported by said rubber bushing. means for forcing a porcelain into telescoped relation with a metal shell on said die, a centering sleeve slidably received in said centering sleeve guide, and means engaging with the lower end 01 said centering sleeve to urge it upwardly, the upper end or said centerin: sleeve being bifurcated and having a downwardly extending conical recess formed therein which is adapted to engage with and center the lower end or the porcelain in the metal shell on said tubular support, said centering sleeve being resiliently positioned for limited lateral move zzsent by said centering sleeve guide and said ubber bushing.

Apparatus for assembling spark plugs is it said positioning sleeve, a rubber bushing carried by said centering sleeve guide and being snug received in the bore oi said positioning sleeve, a centering die slidably received i i ti 8 sleeve d. being supported by said rubber imf, means for forcing a porcelain into telescoped relation with a, metal shell on said die, and a centering sleeve slidably received in said centering sleeve guide, the upper end of said centering sleeve extending upwardly from said centering sleeve guide and being adapted to engage with and center the lower end 01 the porcelain in the metal shell on said tubular support, but to enable limited oflcenter positioning ct untrue porcelains due to the resiliency of said rubber bushing.

5. In apparatus for assemblying spark plan. a positioning sleeve, supporting means received in said positioning sleeve for supporting a spark plug shell adapted to receive a porcelain therein, centering means of appreciably smaller outside diameter than the inside diameter 01 said positioning sleeve received therein and adapted to engage with and center a porcelain carried by a spark plug shell on said supporting means, means resiliently supporting said centering means for vertical movements, and resilient means interposed betwcen said centering means and said nositioning sleeve to center, normally, said centerim means in said positioning sleeve but permit limited lateral movement of said centering means.

8. In apparatus for assembling spark plugs. supporting means for a tubular spark plug shell. centering means for engaging the lower end of a porcelain carried by a supported shell to center it therein, means for resiliently supporting said centering means for vertical movement. a rubber sleeve positioned around said centering means. and confining means for said rubber sleeve for positioning same and limiting the movement thereof said rubber sleeve mounting said centering means :ior limited lateral movement but normally maintaining same in a given centering said supporting means being by said rubber sleeve mount same resilient M. BROWN 

